from random import *
from turtle import *
bgcolor(0,0,0)
ht()
speed(0)
pensize(2)
color(1,1,1)
r = 10
pu()
goto(0,-r)
pd()
acc_ext  = 0
while True:
    color(choice([(0,0,0),(1,1,1)]))
    ext = random() * 90
    circle(r, ext)
    acc_ext += ext
    if acc_ext > 360:
      acc_ext  = 0
      r+= 3
      pu()
      goto(0,-r)
      seth(0)
      pd()